Indicator and control, particularly for paper machines



June' 10, 1941. G, s, wlTHAM, JR 2,244,864

' INDIVCATOKAND ooNTRoL, PARTICULARLY Fon PAPER MACHINES Filed Aug. 25.1937 'Jnentor vGeorcge SM' qmJr.

attorney Patented June 10, 1941 UN-l'reo STATES PATENT OFFICE ymnlca'roa AND jill-igen; ran'rrcmam I n ron raras. mcmnss Georgestanford witham, Jr., Portland, om.

appuiera@ Amm z5, 1937, sex-a1 No. mossi s `climi.. (ci. ss-izs) In themanufacture of paper, maintenance and control of the proper moisturecontent at each stage'of the webs progress is necessary to produce aproduct. of a desired and uniform quality. It is recognized to be ofextreme importance that the moisture content of the finished web bec'orrect, and that the webrcontain neither too much nor too littlemoisture. Various attempts have been made heretofore to indicate,preparatory to regulating, or to regulate, the amount of moisture in thefinished web; but never with entire success.` The plan now mostgenerally used comprises the application toopposite surfaces of the web,or to spa'ced points thereof, of termi*- nals incorporated in a h ighfrequency electrical circuit, and since the conductivityof the paper webto such `current varies in accordance with theJ moisture content, suchdevices furnish an` automatically or through the conscious action 'ofone observing the need for correction.

indication of the moisture content, but this indi'- 4 cation is animperfectone; it is rendered inaccuaccurate indication; furthermore,such devices can only be applied to small areas, and'therefore A theyindicate only the conditions which obtain in the regionof these'areas,and it is found in practice that they are'A not a fair indication of themoisture content of the entire web.

I-have discovered that the width of the web, as

it leaves the driersection, or the caIenderstack, or indeed, at anypoint in its progress, is a direct index of the moisture content of theweb, 4regardless of the character of the paper, ofthequality 'of theflbercontent'of the paper, and like considerations., In other words, thewidth case, to provide 'means which may be operable Y The aboveindicates a specific application 'ofl this invention in a eld ,wheresuch means are and have been long desired. However, it is also ofadvantage to apply `the same principles in other fields. For instance,in the shrinking of textilesit is of importance to indicate correctly,and to initiate corrective measures to govern, the shrinkage of thecloth. In a printing press, or in' any reeling or unreeling operation,shrinkage may be measured as an indication of moisture content, andaccurate knowledge thereof .permits adjustments to be made to improvethe quality of the printed product. In the rolling of metal plates, orsheets, the width vof the sheet is an index of its thickness, and topro'vide accurate means to measure variations in the width of the sheetor plate,`is to provide accurate means to4 determine the thickness ofthe plate. In consequence, it is an object of this invention, moregenerically considered, to provide a means for accurately determiningthe width of the web (including in this term, any sheet, plate orweb-like element), particularly a traveling web, and where its widthvaries in direct relation to some other characteristic, as moisturecontent or thickness, to provide means for indicating, throughindicationsof the ,variation in width, the variations' in this relatedcharacteristic, and as in the former automatically, if desired, tocorrect anydeparture I shrinks by a given degree with the removal of a fgiven percentage of moisture, and Athis shrinkage can be accuratelymeasuredand it can be em*- ployed as a direct ,index of the moisturecontent.

It is therefore, a principal object of my invention, as applied to themanufacture of paper, to give an indication,l more accuratelythan by anymeans or method heretofore known,` of the moisture content of the web,or alternatively, to operate corrective devices by and in accordancewith changes induced by variations in the width of' the web. In thisconnection it may be noted that 'inv the observed characteristic' from adesired normal. y

As .has heretofore been suggested, and as will become apparenthereafter, the indication or measurement of the width of a traveling webarises as a result of variation in the position of, an edge of the web,to dispose that edge, transversely of the direction of movement of theweb, to one side or the other of a normal or desired position. As willbe further apparent hereafter, such variation of the' position of theedge from a normal position may be made to operate auto-` maticallycertain corrective agents. Since these corrective agents may vary widelyin form and lin effect, it follows that departure of the edge of use ofto maintain alignment of the web at any point in its travel, or for anypurpose-for instance, in rerolling, or in feeding the web to a press. Inconsequence, it is a further o bject oi` i this invention to provide ameans suitable to preserve edge-alignment or a traveling web or theWhile the principles of this invention .may he incorporated in variousforms, it is one of the objects 'of the invention to provide suchmechanism which may be operated simply and conveniently through themedium of producing e. differential pressure between the interior of shollow body and the atmosphere in which the web is running; whichdi'erential pressure is variable by variations in the width of the webas it travels past a slit, at opposite sides ot' which the diierentialis applied, thereby making possible the 'measurement ci such variationsin the pressure dierentiai to indicate accurately and directlyvariations in the width o the web,-

though these be small in amount; or if it is variations in some othercharacteristic, dependent upon variations in the width, that is thething to h 'uns .in pressure differential, te characteristic .to be s orat' some stages of can not be contacted elers, and to avoid any the web,it is preferable ve any physical contact tiring devices. it is e suchieelers which,

ment which will indicate the change in moisture content between onepoint and another in the path of -travel ot' such a web.

y Additional objects will become apparent as this specification)progresses` My invention, then, comprises the novel apparatus, bothgenerically and specically. as dis closed diagrammatically in theaccompanying drawing, and as will be more particularly disclosed in thisspeclcation and dened by the claims which will terminate the same.

The accompanying drawing illustrates apparatus suitable to carry out myinvention, and

vsuitable for incorporation in paper making machinery, to indicate or tocorrect for variations in the moisture contento! the web. The drawing ispurely diagrammatical in character.

Figure 1 is, in general, a side elevation of the drier section andcalender stack of a paper malsing machine, illustrating),r my inventionapplied thereto.

Figure 2 is, in general, a plan view of the web with the feelers orcontact members applied thereto, and illustrating diagrammaticallycertain indicating and correcting devices.

Figure 3 is a plan view of such a feeler or contact device, and Figure iis a. cross-section therethrough. showing its relationship to the web.

'Ihe last press rolls of a paper making machine are indicated at l9,from whence the paper .web W passes to the drier section 8 and thence tothe calender stack 1 to be wound uponl a. reel R. The drying rolls Ilare heated by suitable means. such means being customarily steam pipes82 leading from a main I3. The temperature o! the drying rolls 8| iscontrolled by regulating the` v:menace sure regulating valve is shown asrepresentative of means to control the steam pressure and hence thetemperature of the drying rolls. Since these elements are all common inthe art, and form part of the paper machine, with which my invention isnot directly concerned, no further description in detail is believed tobe necessary.

As pointed out above, I have discovered that the width of the web variesin direct ratio to its moisture content; The edges of the web, whenformed, are a precise and known distance apart, l

and as the web is dried, these edges approach one another, and the moremoisture is eliminated, the closer they approach. There is a point ofapproach or spacing of the edges of the web at each point in its travel,which for any given web is the desired normal spacing, corresponding tothe desired proper and normal moisture content for thatvparticular wehat that particular point; and this is true regardless of the weight orthickness oi the paper, the chau-actero its fiber, or any othercharacteristic ci the weh. Accordingly, eelers are provided to contactthe opposite edges of the web, or, one Aedge being guided for movementinA a. given path, to contact the opposite edge of the web and todeterminel the spacing from the nxeci path oi the opposite edge; if,then, the edge oi the weh is inside of such a feeler, or inside of theieelere position for normal width and normal moisturecontent,

toc much moisture has been eliminated, and steps should be taken,manually, or automatically, to lessen the temperature o the dryingrolls. to regulate the quality of the stock, or regulate the atmosphericcondition oi the surrounding air. If, on the other hand, the edge oi theweb is determined by the feeler to he outward of this normal position,not enough moisture has been eliminated from the web, and steps must betaken to increase the temperature of the drying rolls, or reversely toregulate the other factors street; ing moisture content of the web.Regulation of the temperature of the drying rolls is an obvious (andgenerally eective) way of controlling the moisture content of the paperweb, but by no means is it the only way, nor necessarily the sole or theonly way in which moisture control will be effected. Other ways havebeen suggested above, and any of these ways, or indeed any 4suitableway, may be employed, as necessity or experience requires or suggests.However, ipsofar as this specification is concerned, where regulation oftemperature ot the drying rolls is mentioned, this is intended toinclude, as an equivalent, the regulationY of any such Hector assuggested above. y

'Obviously it is impracticable to contact the edge of the web with aieeler pressing inwardly in the plane of the weh. Especially is thisimpracticable when. as in some cases, it is desirable not only tomeasure the width ci the web (as an index ot its moisture content) as itleaves the drier section or the calender-stach, but also to measure thewidth oi the web tor e similar purpose, or for comparative purposes, asit enters the drier section, or evenwhile it is inthe papermakingsection. Accordingly,-the feelers are in eiect elements which are placedbeneath the'edg'e of the web, but not necessarily in contact with thesurface of the web,to be covered more or less by the web as the-web'varies in width. In using the word beneath" ll do not intend to implythat the teeleris below the web-only'tlint the ieeler, whether above orbelow the "'wb'is beneath it to the'extent that the web in part.

at least, covers the feeler, and is the more uncovered by the web as thelatter is of less width, or as its covering edge shifts inwardlyrelatiye to the feeler. The feelers are sensitive toV such .covering oruncovering by the web, or alternatively, they aifect some otherinstrument which is sensitive to the covering A,or Vuncovering of thefeeler, thereby generating a forcethe amount a photo-electric cell, orit may be a target upon which such .a cell is directed. The feeler mayproject a medium, in this instance light, or may be the target for aprojected medium such as alight ray; or the feeler m'ay take the form ofa device to enable the creation o f a pressure difierential on oppositesides of a narrow slit or other opening extending transversely of theweb, which slit, by reason of itsl being covered to a greater or lesserdegree, eifects. variationsin the pressure dierential at theoppositesides of the slit, and this in turn will operate indicating or automaticcorrecting devices. .It is immaterial whether the pressure dierential becreated by a higher'external pressure acting upon the web and inwardlythrough the slit, or acting from the slit outward upon the web.

Thus, as is best shown in Figures 2, 3, and 4 the feelei' I may take theform of a small tube constituting a chamber lll within which a pressuremay be created by suitable means, which pressure is permitted to escapethrough a narrow slit or other small opening shown at il, andextendinggenerally transversely of the edge of the web,

and just beneath an edge of the web and in contact with the surface otthe web. Pressure is supplied, for instance, by a line 2 past regulatingmeans indicated at 20, which will 'produce in the line 2 a constantpressure, and past an orifice 29 the capacity of which is equal t thetotal capacity of the slit or slits supplied by this line. The pressurein the line 2 affects a pressure sensitive element such as the Sylphonbellows 2l, and by its action upon an arm 22 therehmay be indicated,upon a chart or drum 2l, any variation in the pressure in the line 2.'I'he slit ll is very uncover the slot .il to a greater degree: thus thepressure can escape. or if it hasbeen permitted partly to escape,` itwill escape with greater facil-- ity, with -the result that pressurewithin the chamber l'is lowered. 'I'his lowering of the pressure isimmediately communicated tothe --sy1pnon 2|, and to cream z2, andindicated upon thedrum 22, with the result, it the' device is to bemanually controlled, that measures are taken by the 'attendant todecrease the temperature of-.the dryingrolls by reducing the pressure ofsteam therein. If an automatic control is desired, there may be mountedupon the arm 22 a suitable contact 24 which will engage with spacedcontacts 25 and 28, in circuit with an electrically energized controldevice 28 operatively` connected to the steam valve 80 to move fthelatvter in a direction to compensate for the greater or lesser moisturecontent which is found in the Aweb at the point A. Alternatively, asindicated earlier in this specification, the manual or theautomaticcontrol may effect variations in the character of the rawmaterial, intheatmospheric condition in the conversion room, in themechanics o f conversion, or in any material or condition airectingmoisture content. The arrangement shown and described is purelyillustrative and rather primitive in character, and any suitable controlmaybe employed, it being the purpose only to indicate how, through themedium of variations in the width of the web due to variations in themoisture content thereof, suitable indications can be given andcorrections autonarrow,.say .007 or .008 inch, and ofl'ers considerableresistance to relief of pressure through it,

and the more of its length iscovered, the greater is this resistance. Ifit is fully covered the resistance is 'the maximum permitted by the con,stant pressure device 2l; if it is fully uncovered the pressure mediumescapes from the slit as fast as it passes the orifice 29, and there isno pressure in the line beyond this oriiice.V

It will be evident that since the slot l I is nearly or substantiallywholly covered by the edge of the web when the latterisof normal width,correfeeler, located at the point A, preferably betweenAthecalenderstack1andtheheelR.willbe acted upon by tbe consequentlynarrower web to maticallyr made; or the condition may be simultaneouslyvand automatically corrected for and indicated to an attendant,

Preferably at the point A two such feelers l are provided at oppositeedges of the web, and

in this case if one edge of the web is not guided to run precisely inatrue path, without variation to one side or other of that path, theindication -wll still be correct inasmuch as the pressure within eachchamber I0 .will be the aggrega of the pressure as it is affected by thetotal length oi' the slits Il in the two feelers l at opposite edges ofthe web.' If -the edges of the web shift to one side or the other,without any change in the width of` the web itself, while one slit willbe opened a greater amount the slit in the opposite feeler will beclosed by the same amount and the aggregate pressure in theinterconnected feelers will be identical, and in consequence, there`vwill be no adjustment and no change vin the indication. If, however.there is a change in the width of the web, the combined length of theslits in the two feelers will change, .and suitable indications willappear and correction be made.

. It is preferable also in some instances to provide a feeler or feelersat/the point B or near in the passage of the web through the drier.section.y There may be .provided an indicator 23 to indicate the widthof the web at the point B or to indicate any changes in its'width atthat point. This indicator 2l is, or may be in all respects analogous tothat shown at 22. but isr` connected to the line 2 past individualconstant Y pressure and orifice controls, separate from those anuncia Itmay be`desirable to accommodate the niachine to webs of dierent width,or because oi varying temperature conditions or other conditions, toeect adjustment ofthe eeler l inwardand outward of the edge or the web.To this end, each such feeler, or at least one of each pair at theopposite edges of the web, is mounted in a support i2 which is fixed inposition, and which carries a screw i3, engageable with a threaded lugou the tube i, whereby1 by a tine adjustment the tube may be movedinwardly or outwardly of the edge of the web.

Since the tube is thus adjustable, it is' necessary to provide for theconnection of the pressure line 2 through nexible connections or thelike, as

' indicated at l in Figure 3.

. While heretoiore the feeier i has been described as a single slittedtube, disposed only along or beneath one surface oi' the web, thisdescription has been purely for simplicity of understanding. Such s.single ieeler-will operate, and by itself is within the scope of myinvention, but for most satisfactory operation it is preferred that itbe constituted as two such slitted tubes, one at one surface or the weband one directly opposite at the other surface of the web, and bothconnected to a common pressure line through a constant pressure device2B and oriiice 2d common to the two feelers. The arrangement is shown inFigure Ai.

Thus arranged, pressure from one (designated for convenience the iowerone) tends to lift the web; substantially equal pressure from the other(designated, to distinguish it, the upper one),

directed immediately towards and opposing the pressure from the lowerfeeler, tends to press down the web. As a result, the web tends to oatmidway between the upper and lower feelers, but

to contact neither. iii the webs edge moves inwardly, both the upper andlower feelers havev their slits uncovered by the same amount, and beingconnected in parallel to the same constant pressure and constant volumedevices 20 and 29,

' the reduction in pressure within their chambers -as an indication oithe lesser thickness. if the web exceeds the maximum desired thickness,the interruption o the iets( is graeter, or may be total, and theincreased vpressure indicates the greater thickness. l

it will now be evident that the line 2, instead of supplying pressure tothe interior chamber llo of the members l, might insteadproduce areduced pressure within that chamber, so that the medium, air, isprojected through the slit il from the open atmosphere into theinterior. It will .be further evident that the vrnember l might also beformed as the target of a photo-electric cell, or might be the cellitself, so that the strength or the current is a iunction oi the amountof coverage Aci the member i, which of course is dependent upon theposition of th? edge oi the web.

Zity will also be evident that the invention is -applicable with equalfacility to the measurenient of the width of any'web: for instance. inthe shrinking of textiles, as previously mentioned, or in the rolling ofplates and sheets. Since, inthe latter instance, the width of the plateor sheet is a function of its thickness, a similar arrangement to thatdescribed may be provided to measure, and ii desired, to correct thethickness of the plate or sheet in accordance with variations in its`width which are a direct result of variations in its thickness. Theinvention, therefore, generically considered, is a device and a methodfor measuring and indicating (including -ilie conception of correcting)variations in the position of an edge of or in the width of a web,usually a traveling web, and for indicating variations. incharacteristics such 'as moisture content, thickness, character ormaterial or workmanship, atmospheric conditions in the conversion room,in the mechanics of conversion, in the adjustment of the machine itself,or in of the many characteristics or conditions which aectan'd which area direct function or criterion of variations in the width of the web.

What I claim as my invention is:

l. Means to determine the width of a traveling web,7 comprising twointerconnected hollow members, disposed beneath but substantially out ofcontact with opposite edges of the web, and each having a small slitextending transversely of the adjacent edge of the web, in position tobe masked more or less in accordance with variations in the width of theweb, means to create a pressure differential, through the slits, betweenthe interior of said members and the atmosphere, which pressurediierentiai will vary in amount fin. accordance with the aggregateamount of through their slits, which pressure dierence will vary inamount in accordance with the aggregate amount of masking ci the slitsby the dispiacernent of the edge o the web. as the web varies in width,and indicating means responsive-to such changes in the pressuredifference.

3. Means to denlnine the width oi a troveiing Web or the like,comprising two interconnected hollow members, disposed beneath oppo@site edges of the web and each having a, smali slit extendingtransverselr1 ci the adjacent edge of the web, in position to be mashedmore or less, in accordance with variations in the width of the web,means to adjustA one such member, relative to the other, transverse-lrof the web, means to create a pressure diderence between `the atmosphereand the connected interior of said members, through their slits, whichpressure diierence will vary in amount in accordance with the aggregateamount of masking of the slits by the opposite edges of the web, andindicating means responsive to such changes in the pressure difference'.

GEORGE STANFGRD WITHAM, 3s.

